Definition
Electrocardiogram (ECG) is a graphical recording of electrical activity of the heart detected by means of surface electrodes and measured using a galvanometer.
Components of ECG
The components of an ECG (Electrocardiogram) represent different phases of the heart’s electrical activity. Here are the key components:
- P Wave:
- Represents atrial depolarization, which is the electrical activity that triggers the atria to contract.
- PR Interval:
- The time between the start of the P wave and the beginning of the QRS complex.
- Indicates the conduction time from the atria to the ventricles.
- QRS Complex:
- Represents ventricular depolarization, which triggers the ventricles to contract.
- It consists of three waves:
- Q Wave: A small downward deflection.
- R Wave: A large upward deflection.
- S Wave: A downward deflection following the R wave.
- ST Segment:
- The flat section between the end of the S wave and the start of the T wave.
- Represents the time between ventricular depolarization and repolarization.
- T Wave:
- Represents ventricular repolarization, which is the recovery phase of the ventricles.
- QT Interval:
- The time from the start of the QRS complex to the end of the T wave.
- Indicates the total time for ventricular depolarization and repolarization.
- RR Interval:
- The time between two consecutive R waves.
- Used to calculate heart rate.
Purposes
- To assess the cardiac function (rate, rhythm, and conduction).
- To diagnose cardiac rhythm disorders (e.g. heart block and dysrhythmias).
- To diagnose cardiac diseases (e.g. myocardial infarction).
- To detect the effects of electrolyte imbalance on cardiac function (e.g., hyperkalaemia, hypokalaemia, etc.).
- To evaluate the effects of treatment (e.g. administration of cardiac drugs).
Articles
- ECG machine.
- Electrodes for 12-lead ECG.
- Electroconductive gel.
- Front open gown or shirt for patient.
- Tissue paper.
Preparation of the Patient
Preparing a patient for recording an electrocardiogram (ECG) involves several key steps to ensure accurate results and patient comfort:
- Clothing and Accessories:
- Ask the patient to remove any jewelry, watches, or metallic items that could interfere with the ECG.
- Ensure the patient wears loose, comfortable clothing or provide a gown for easy access to the chest, arms, and legs.
- Skin Preparation:
- Clean the electrode sites (chest, arms, and legs) with alcohol wipes to remove oils or dirt.
- Shave any excessive hair at the electrode sites to ensure proper adhesion of the electrodes.
- Positioning:
- Position the patient comfortably in a supine position (lying flat on their back) on the examination table.
- Ensure the patient is relaxed and breathing normally to avoid muscle tremors or movement artifacts.
- Communication:
- Explain the procedure to the patient, addressing any concerns or questions.
- Reassure the patient that the test is painless and non-invasive.
- Electrode Placement:
- Attach the electrodes to the appropriate sites on the chest, arms, and legs, following the standard 12-lead ECG placement guidelines.
- Ensure the electrodes are securely attached to avoid signal interference.
- Environment:
- Ensure the room is quiet and at a comfortable temperature to prevent shivering or sweating, which can affect the results.
Procedure
| Nursing actions | Rationale | |
| 1. | Before procedure Explain the purpose of ECG and procedure to the patient. Reassure patient that procedure is painless and safe. | Helps to gain patient’s cooperation and reduces anxiety regarding procedure. |
| 2. | Ask female patients to remove all tight-fitting clothing around the chest. Assist patient to put on a front open loose gown or shirt. | Procedure requires placement of electrodes over chest area. |
| 3. | Place the machine close to the patient bed and connect to wall outlet. Ensure that the ECG machine is in functioning order. | |
| 4. | Ensure proper standardization of the machine: Enter menu button by pressing knob and select the desired aspect. Select EKG in menu, select lead = 3 X 1.Set paper speed at 25 mm/min.Set gain 10 mm/mv. Provide standard 1 mV signal to ECG machine so that the spike made will be 10 mm or 2 mm large squares in height.Select PRINT in menu and select diagnosis option in mode setting.Set wave size to 2-9.Ensure that the machine is properly earthed. | Proper standardization of the machine ensures a precise recording of ECG. |
| 5. | During procedure Verify the physician order and identify the patient. Ask the patient to lie in supine position and be as relaxed as possible. If the patient needs to be transported to the ECG department, transport him on a trolley. Never allow him to walk till diagnosis is confirmed. | Rigid posture and contraction of muscles may result in artifacts on ECG record. |
| 6. | Provide privacy by pulling the curtains around the patient. | Procedure requires exposing chest area, which is embarrassing for the patient. |
| 7. | Expose chest completely, apply electroconductive gel on lead placement sites, and position all electrodes appropriately: Check for color codes of limb leads and connect limb electrodes to all four extremities as per the manufacturer’s code. | |
| Place suction electrodes at appropriate sites: V1-4th intercostal space on the right side, parasternal. V₂-4th intercostal space on the left side, parasternal. V3-midway between V₂ and V4.V4-5th intercostal space on the left side in the mid-clavicular line. V5-5th intercostal space on the left side in the anterior axillary line. V6-5th intercostal space on the left side in the mid-axillary line. | ||
| Ensure proper contact between the lead and skin. Shaving of the chest may be required in case of male patients. | Proper contact between skin and electrodes and proper placement of electrodes are very essential for obtaining a good recording. | |
| 8. | Instruct the patient that you are going to start the recording and he/she should lie still in the bed without moving till the recording is complete, which may take 5-10 minutes. | Patient’s movement during recording causes artifacts on ECG record. |
| 9. | Record the ECG: Manual recording: Record limb leads (I, II, III, AVR, AVL, AVF) by advancing the machine settings to the respective leads. To record chest leads (V1-V6), advance the suction electrode to next position after recording each lead (ensure that machine is set for chest lead recording). Record long lead II. Automatic recording: Place limb as well as all chest electrodes in position and ask for auto recording. | |
| 10. | Check the ECG record for appropriateness and presence of artifacts, if any. | In case of inappropriate recording or presence of artifacts, recording needs to be repeated. |
| 11. | After procedure Inform patient that ECG recording is completed. | |
| 12. | Remove electrodes from all four limbs and chest; wipe off the Electroconductive gel using tissue papers; assist patient in dressing. | |
| 13. | Wipe off the electroconductive gel from electrodes. | After drying, the gel forms a crust over the electrodes which may interfere with future recording. |
| 14. | Label the ECG: Write patient’s full name, inpatient/ outpatient number, date and time of recording.Record lead identification in case of manual records.A standard lead should be labeled and pasted on ECG card when manual records are obtained. | Provides accurate identification data. |
| 15. | Read and report ECG as follows: Rhythm. Conduction intervals. Cardiac axis. A description of the QRS complexes. A description of the ST segments and T waves. | Helps to identify obvious gross abnormalities. |
| 16. | Show ECG record to the physician as soon as possible so that further treatment orders can be obtained, if any. |
Special considerations
Note that the following can cause poor ECG signal and/or artifacts on an ECG record.
- Oily, dirty, and scaly skin.
- Dirty or encrusted electrodes.
- Improper application of electrodes.
- Loose or dislodged electrodes.
- Patient’s movement.
- Muscle tremor.
- Broken cable wire.
- Faulty grounding.
REFERENCES
- Annamma Jacob, Rekha, Jhadav Sonali Tarachand: Clinical Nursing Procedures: The Art of Nursing Practice, 5th Edition, March 2023, Jaypee Publishers, ISBN-13: 978-9356961845 ISBN-10: 9356961840
- Omayalachi CON, Manual of Nursing Procedures and Practice, Vol 1, 3 Edition 2023, Published by Wolters Kluwer’s, ISBN: 978-9393553294
- Sandra Nettina, Lippincott Manual of Nursing Practice, 11th Edition, January 2019, Published by Wolters Kluwers, ISBN-13:978-9388313285
- Adrianne Dill Linton, Medical-Surgical Nursing, 8th Edition, 2023, Elsevier Publications, ISBN: 978-0323826716
- Donna Ignatavicius, Medical-Surgical Nursing: Concepts for Clinical Judgment and Collaborative Care, 11th Edition ,2024, Elsevier Publications, ISBN: 978-0323878265
- Lewis’s Medical-Surgical Nursing, 12th Edition,2024, Elsevier Publications, ISBN: 978-0323789615
- AACN Essentials of Critical Care Nursing, 5th Ed. Sarah. Delgado, 2023, Published by American Association of Critical-Care Nurses ISBN: 978-1264269884
- Ernstmeyer K, Christman E, editors. Nursing Fundamentals [Internet]. 2nd edition. Eau Claire (WI): Chippewa Valley Technical College; 2024. PART IV, NURSING PROCESS. Available from: https://www.ncbi.nlm.nih.gov/books/NBK610818/
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